DCL-10-146, Response to Telephone Conference Call Held 11/10/2010 Between U.S. Nuclear Regulatory Commission and Pacific Gas & Electric Co. Concerning Responses to Requests for Additional Information Related to License Renewal Application

Response to Telephone Conference Call Held 11/10/2010 Between U.S. Nuclear Regulatory Commission and Pacific Gas & Electric Co. Concerning Responses to Requests for Additional Information Related to License Renewal Application

ML103280467
Person / Time
Site:	Diablo Canyon
Issue date:	11/24/2010
From:	Becker J Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-10-146
Download: ML103280467 (5)

Text

Pacific Gas and Electric Company James R. Becker Diablo Canyon Power Plant Site Vice President Mail Code 104/5/601

p. O. Box 56 Avila Beach, CA 93424 805.545.3462 November 24 , 2010 Internal: 691.3462 Fax: 805.545.6445 PG&E Letter DCL-1 0-146 u.s. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20852 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Response to Telephone Conference Call Held on November 10, 2010, Between the U.S. Nuclear Regulatory Commission and Pacific Gas and Electric Company Concerning Responses to Requests for Additional Information Related to the Diablo Canyon Nuclear Power Plant. Units 1 and 2, License Renewal Application

Dear Commissioners and Staff:

By letter dated November 23, 2009 (Reference 1), Pacific Gas and Electric Company (PG&E) submitted an application to the U.S. Nuclear Regulatory Commission (NRC) for the renewal of Facility Operating Licenses DPR-80 and DPR-82, for Diablo Canyon Power Plant (DCPP) Units 1 and 2, respectively. The application included the license renewal application (LRA), and Applicant's Environmental Report - Operating License Renewal Stage.

On November 10, 2010 a telephone conference between the NRC and representatives of PG&E was held to obtain clarification on the applicant's response to request for additional information (RAI) submitted to the NRC in a letter dated September 30, 2010, regarding the One-Time Inspection of ASME Code Class 1 Small-Bore Piping aging management program.

PG&E's supplemental information to the RAI response for which the staff requested information is provided in Enclosure 1. PG&E revises a commitment in revised LRA Table A4-1, License Renewal Commitments, shown in Enclosure 2. LRA Amendment 26 is included in Enclosure 2 showing the changed pages with line-in/line-out annotations. Enclosures 1 and 2 supersede previously submitted information regarding the One-Time Inspection of ASME Code Class 1 Small-Bore Piping aging management program.

If you have any questions regarding this response, please contact Mr. Terence L. Grebel, License Renewal Project Manager, at (805) 545-4160.

Document Control Desk PG&E Letter DCL-10-146 November 24 , 2010 Page 2 I declare under penalty of perjury that the foregoing is true and correct.

Executed on October 8, 2010.

TLG/50361762 Enclosure cc: Diablo Distribution cc/enc: Elmo E. Collins, NRC Region IV Regional Administrator Nathanial Ferrer, NRC Project Manager, License Renewal Kimberly J. Green, NRC Project Manager, License Renewal Michael S. Peck, NRC Senior Resident Inspector Alan Wang, NRR Project Manager

Enclosure 1 PG&E Letter DCL-10-146 Page 1 of 1 PG&E Supplement to Telephone Conference Call Held on November 10, 2010, Concerning Response to Request for Additional Information (RAI) Submitted to the NRC in a Letter Dated September 30, 2010, Regarding the One-Time Inspection of ASME Code Class 1 Small-Bore Piping Aging Management Program Diablo Canyon Power Plant (DCPP) will volumetrically examine 10%, with a maximum of 25, of the small bore socket welds and 10%, with a maximum of 25, of the butt welds within the population of ASME Class-1 piping NPS less than 4-inches on each unit.

Currently, DCPP has 696 socket welds in Unit 1, 841 socket welds in Unit 2, 134 butt welds in Unit 1, and 133 butt welds in Unit 2. Based on the current weld count, this would result in the examination of 25 socket welds for Unit 1, 25 socket welds for Unit 2, 13 butt welds for Unit 1 and 13 butt welds for Unit 2. DCPP may perform opportunistic destructive examination of welds in lieu of volumetric examination with 1 destructive examination being equivalent to 2 volumetric examinations. The sample selection methodology will take into account damage mechanisms such as thermal fatigue, vibration induced fatigue, and stress corrosion cracking. DCPP will determine potential damage mechanisms for each weld by using site specific analysis, MRP-146 guidance, and plant operating experience. These documents currently show thermal fatigue as the prevalent damage mechanism. Plant operating experience will also be considered for the socket weld examination sample to validate the effectiveness of past corrective actions.

The volumetric examination of these welds will occur within 6 years prior to the period of extended operation.

The commitment in LRA Table A4-1 has been revised to inspect 10%, with a maximum of 25, of the small bore socket welds and 10%, with a maximum of 25, of the butt welds within the population of ASME Class-1 piping NPS less than 4-inches on each unit. See revised LRA Table A4-1 in Enclosure 2.

PG&E Letter DCL-10-146 Page 1 of 2 LRA Amendment 26 LRA Section Table A4-1

Enclosure 2 Appendix A PG&E Letter DCL-10-146 AGING MANAGEMENT PROGRAMS Page 2 of 2 Table A4-1License Renewal Commitments Item # Commitment LRA Implementation Section Schedule 39 DCPP will volumetrically examine 10%, with a maximum B2.1.19 During the 6 of 25, of the small bore socket welds and 10%, with a years Pprior to maximum of 25, of the butt welds within the population of the period of ASME Class-1 piping NPS less than 4-inches on each extended unit. Currently, DCPP has 696 socket welds in Unit 1, operation 841 socket welds in Unit 2, 134 butt welds in Unit 1, and 133 butt welds in Unit 2. Based on the current weld count, this would result in the examination of 25 socket welds for Unit 1, 25 socket welds for Unit 2, 13 butt welds for Unit 1 and 13 butt welds for Unit 2. DCPP may perform opportunistic destructive examination of welds in lieu of volumetric examination with 1 destructive examination being equivalent to 2 volumetric examinations. DCPP will volumetrically examine 25 small bore welds per unit within the population of ASME Class-1 piping NPS 4-inches and less. The sample will contain socket welds and butt welds proportional to the number of socket welds and butt welds within the population. Based on the current weld count this would result in 8 butt welds and 17 socket welds in DCPP Unit-1 and 7 butt welds and 18 socket welds in Unit-2. The volumetric examination of these welds will occur within 10 years prior to the period of extended operation.